Recently, non-contact IC tag has been demanded in many fields including the physical distribution, and reduced costs and an increase in performance have been required therefor.
In addition, various mass storage memory cards have been widely used in portable digital equipment such as a digital camera, a portable music player or a portable information terminal along with the spread of the memory cards.
In recent years, to widen the application of a memory card further, it has been demanded to have a wireless communication function.
In response to such demands, an SD memory card (registered trademark) having a wireless interface function added thereto is disclosed (for example, see Japanese Unexamined Patent Application Publication No. 2001-195553).
The disclosed SD memory card incorporates not only a main functional unit as a storage medium but also a wireless controller, and is configured so that an antenna module formed of a loop antenna is connected to the wireless controller through an interface. A flash memory serving as a storage medium functions as a flash ROM for a memory used in the SD memory card, and stores a driver program for operating a wireless communication function.
With such a configuration, the SD memory card connected to the antenna module can communicate with an external wireless communication device since radio waves are transmitted and received to/from the antenna module by using the wireless communication function. In addition, a configuration in which the antenna module is built in a casing of the SD memory card is also disclosed.
In addition, an IC card which achieves a reduction in size and includes a transceiving coil for preventing communication failures therein is disclosed (for example, see Japanese Unexamined Patent Application Publication No. 8-16745).
The IC card is configured so that a magnetic substance having high magnetic permeability and high resistivity is deposited or adhered on a rear side of a substrate on which an IC chip and the transceiving coil are mounted. In addition, when the IC card mounted on a reading unit transmits and receives information, the magnetic substance prevents electric power loss of the reading unit caused by magnetic flux of an electromagnetic field of radio waves and an eddy current that is generated from a metallic conductor such as a battery. Specifically, the magnetic flux is shielded by the magnetic substance, and thus an occurrence of eddy current in the metal conductor caused by the magnetic flux is prevented.
In addition, in Japanese Unexamined Patent Application Publication No. 8-16745, there is also disclosed an IC card configured so that an IC chip is mounted on a first print board, a transceiving coil is formed on a second print board, and a magnetic substance is interposed between two print boards. With such a configuration, it is possible to increase the storage capacity due to enlargement of an area on which the IC chip is mounted, and it is also possible to miniaturize the IC card in a case where the storage capacity is not increased.